To investigate the tolerability, safety, and efficacy of "drug holiday" (withdrawal of antiparkinsonian medication) for the treatment of Parkinson's disease. Specifically we will investigate: 1. The acute effects of antiparkinsonian medication withdrawal on autonomic function. 2. The acute effects of a 4 day drug holiday on the responsiveness of the post synaptic dopamine receptor. 3. The chronic effects of a 4 day drug holiday on medication requirements, medication response, drug-induced hallucinations, sleep quality and quality of life in patients with complicated Parkinson's disease. 4. The safety of a 4 day drug holiday in patients with complicated Parkinson's disease.